Thermostatic switch control



Patented June 5, 1928.

JUSTUS C. GOOSMANN, OF PEOR IA, ILLINOIS.

a I THERMOSTATIC SWITCH CONTROL.

1 Application filed March 3, 1921. Serial No. 449,487.

This invention relates in general to switch controls, and more particularly. to thermostatic controls, by which a switch is automatically thrown in and out at predeter- 5 mined temperature variations. NVhile this control is capable of use for a variety of purposes, it is especially adaptedfor use in-connection with refrigerating apparatus for the purpose of starting the driving motor when the temperature in the refrigeratiing chamber reaches a predetermined maximum, and for stopping said motor and thereby the apparatus when the temperature in the chamber reaches apredetermined mini- 5 mum.

.One of the purposes of this invention is to provide a control of the character indicated, which will be accurate and reliable in operation, which is capable of adjustment to vary the range of temperatures at which the switch will be actuated. and also to vary the minimum temperature at which the switch will be actuated, and one which will be simple in construction, cheap to manufacture, and not liable to get out of order in operation.

Another feature of my invention resides in the novel structure employed for maintaining the thermostatic element, in the present instance an expansible member, in proper alignment so that there will be no binding or undue friction between moving parts which might detract from the reliability of the apparatus, and whichrwill prevent the member from twisting and becomingdistorted so as to interfere with its accuracy of operation.

Other advantageous features of my invention should be readily appreciated as the' same becomes better understood by reference to the following description when considered in'connection with the accompanying drawlngs. Referring to the drawings: trol embodying my invention;

Fig. 2 is a transverse sectional view taken on the line 22 of Fig. 1; and Fig. 3 is a longitudinal sectional view lpoking toward the right at. Fig. 1. By reference to the drawings, it will be observed that my invention embodies a frame upon which the operating parts are mounted, comprising a base 5, an upright 6,

bracket 8 upon which the switch, desig- Fig. 1 is a side elevation of a switch con a top portion 7, and an upwardly extending.

switch comprising a pair of terminals 11, ar-

ranged in spacedrelation, one of which only is shown in Fig. 1, and a. contact member 12 pivotally mounted at 13 upon a lever 14 fulcrumed in the switch casing at 10, this member being adapted to be swung from open position shown in Fig. 1 to closed position, wherein it contacts with the terminal 11. An expansion spring 15 serves to throw the switch to open or closed position when the lever 14 is swung on its fulcrum past a dead center line connecting the fulcrum 10 with the longitudinal axis of the contact member.

Obviously, any other preferred type of snap switch might be employed.

The lever or switch arm 14 is actuated by a thermally responsive element, consisting in the present instance, of an expansible bellows 16 of well known construction, adapted to be filled with a suitable fluid readily cxpansible under the action of beat, this element being rigidly secured at one end to the base 5 of the frame by means of an extension 17 upon which a nut 18 is threaded. Since it is desirable in most instances. that the element be located remote from the chamber.

the temperature of which is to be controlled, I employ an extension tube 19 connected at one end with the element, and at its other end with a thermostatic member 21 of tubular shape, and closed at its outer end. This member may, if preferred, be made of copper or other metal having a relatively high coefficient of expansion, in which instance, it is preferable to employ afluid in the bellows and thermostatic member which is not readily. expansible under the action of heat, the expansion and contraction of the tubular member 21 being relied upon to displace suf ficient fluid to cause the desired actuation of the bellows.

Preferably, however, the member 21 is made of non-expansible material, and the bellows and this member are filled with a fie'd sulphur dioxide,

I I I i 1 i I v flllld readlly sensible to heat, such as hque for instance, the expansion of this fluid under the action of'heat being relied upon to elongate the bellows,

which automatically contracts. (as will be hereafter explained) as the pressure therein diminishes upon the contraction of the fiuidQ Upon the unattached or free end22of the bellows there is mounted a flange disc 23,

this sleeve 26 downwardly or upwardly, the

' ished respectively, 20

against which the lower end of an expansion spring 24 abuts. The upper endxof this spring engages a similar, but oppositely disposed disc-25, andthe normal tension of this spring may ':be regulated by an adjustable sleeve26, threaded-through a tapped opening in the top 7/-0f the frame. By threading tension on spring 24;is increased "or diminby I which adjustment, the opposition of spring expansion of the bellows may be regulated so that the temperature at which initialexpansion of the bellows will take place may be controlled to a fine degree of 'nicety.

An operative connection between the bellows and the snap switch lever 14 is provided, this connection consisting of a rod 27 Y 28, consisting in this instance, f slots 31' attached at its lower end to the bellows and a rod 28 attached at its upper end to the switch lever 14 through the intermediary of a connecting element 29. A lost motion connection is provided between the .rods 27 and formed in a sleeve 32 at the lower end of rod 28 in which a pin 33 projecting at opposite sidesof the telescopic end 34 of the rod 27 is adapted to work. For purposes'of regulating the range of temperatures between the extremes of which the switch willbe operated'by the bellows, I employ a coiled expansion spring'35 surrounding the telescopically connected portions of the connecting rods, the lower end of this spring being adapted to bear against a flanged collar 36 mounted upon the rod 27 and its upper end-against an adjustablenut 37, which is locked in adjusted position by a lock nut 38.

I It will be obvious, as previously explained,

- through the rod 27 by'reason of the lost motion connection between this rod and rod 28, and therefore, the bellows element is protected against the jars and shocks to which it 24 to the longitudinal would otherwise be subjected were the yieldable connection above described-not provided. Upon reverse or contracting movement of the element, the rod 28 will be pulled downwardly by the pins33, pulling against the lower end of the slots 31, and when the switch'is actually thrown by the spring 15, the quick downward movementof rod 28 will again be absorbed by the spring and lost motion connection and will not be "transmitted to rod 27 and the element.

Since the element is mounted at one end only on the frame, there is a tendency during its expansion and coiitraction movements to twist or becomeldistorted or disposed out of proper alignment, with the result that these various working parts may be caused to bind so as to detractfrom thereliability of the apparatus. For the purpose 'of maintaining the element in the proper alignment without imposing a friction which would retard its movements, I have provided a guiding construction as follows: At opposite sides of the element, the base 5 is equipped with upwardly projecting lugs 39, the outer .vertical faces of which are horizontally grooved to accommodate the inturned ends 41 of a pair of vertically disposed yokeshaped members 42. A The centralupwardly extending portions 43 of these yoke-shaped members are disposed in opposed relation at opposite sides of the free end 44 of the element. These portions are provided at'their inner faces with horizontal grooves 45 and the cylindrical portion of the element is likewise provided on opposite faces with' 'horizontalgrooves 46. Guiding elements 47, having their ends beveled to provide knifeedged bearings in the grooves 45 and 46 respectively, are interposed between the I members 42 and the free end of the element, and the parts are all-held inoperative position by a pair. of tractile springs '48 connect ed at opposite ends tothe yokes, 42.

It will be obvious that the members 42 are prevented from tilting laterally by reason of the spaced relation'of the bearing lugs 39. Consequently, twisting orf' tilting movements. of the free end of the element are prevented by the elongated bearing surfaces of the guiding elements 47. These elements, however, being pivotally related with the. element and with the yoke members, do not interfere with the longitudinal expansion and contraction of the element, nor do they impose any frictional resistance to its move- .ments, with the result that the element is maintained in proper alignment, but its accuracy is not diminished by frictional resistance. s.

'It is believed that the construction, operation, and many of the inherent advantages of this invention will be apparent from the foregoing without further description, and while I have shown and described a preferred embodiment of the invention, obviously, the details of construction may be varied within considerable limits without departing from the essence of the invention, as defined I spring, and an adjustable spring tending to resist the expansion of said element.

2. In a switch control, the combination of a switch, an expansible heat-actuated element, a pair of r6ds connected with said switch and said element respectively, a lost motion connection between said rods, an adjustable spring normally urging said rods apart, a spring a'rranged'to yieldin 1y resist the expansion of said element, an means for regulating the tension of said'last-mentioned spring.

3. In a switch control, the combination ofi a switch, an expansible heat-actuated element, a connection between said element and said switch, means for yieldingly resisting the expansion 'ofvsaid element, and resilient means acting upon the movable end of said element for maintaining said element in predetermined alignment during the expansion and contraction thereof.

4. In a switch control, the combination of a switch, a thermostatic element, operative connections between said switch and said element, and yieldably mounted means engaged with the movable end of said element for maintaining the same in predetermined alignment. I

5. In a switch control, the combination of a frame, a thermostatic element fixed at one end thereto, a switch, an operative connection between the free end of said element and said switch, a pair of members mounted on said frame at opposite sides of'said element, guiding members pivotally en aging said members respectively and the Iree end of said thermostatic element, and springs arranged to hold said members and elements in operative position.

6. In a switch control, the combination of a frame, a thermostatic element fixed at one end thereto, a switch, a connection between the free end of said element and said switch, a pair of members pivotally supported by said frame at opposite sides of said element, a guiding element disposed between each of said members and the free end of said thermostatic element, nd. springs for urging said members towar each other.

7. In a switch control, the combination of a frame, a thermostatic element attached thereto at one end, a pair of members pivot ally supported on said frame at opposite sides of said element, guiding elements disposed between said members and the free end of said element and having elongated knife-edged bearings engaging said element and said members, and tractile springs connecting said members to retain said guiding elements in operative position.

8. In a switch control, the combination. of a frame, a'thermostatic element attached at one end thereto, a switch carried by said frame remote from said element, a yieldable connection betweensaid element and said switch, a spring normally resisting the expansive movements of said element, means for regulating the IGIISIOI! of sald spring,

and means for maintaining said element in alignment, said last-mentioned means including a plurality of guiding elements pivotally engaged with said'thermostatic element, and means for yieldingly retaining said guiding elements in position.

J USTUS G. GOOSMAN N. 

